This invention relates to liquid separators for separating heavier and lighter fractions in a mixture of liquids. It is particularly concerned, although not necessarily exclusively so, with the separation of water from a lighter liquid such as diesel fuel.
Water separators are employed in the inlet feed lines of diesel engines because of the ill effects that can be caused by even small amounts of water contamination of the fuel. Known apparatus often relies on the difference in densities between the two liquids to achieve separation of any water from the fuel flow, as for example in GB Nos. 1113621 and 1234022. In the example of GB No. 1234022, the entering flow is made to swirl around a frusto-conical outlet conduit, so tending to throw any heavier fraction, in particular water in the fuel, outwards away from the conduit. When the flow comes adjacent the inlet to the conduit, a sharp change of direction is imposed on the liquid, so that drops of water it contains are further restrained from entering the outlet conduit and eventually settle to be discarded.
There can still be a problem, however, if water is present in the form of extremely small droplets suspended in the fuel because these tend to separate out only very slowly. If the speed of flow of the liquid is too fast or if conditions are too turbulent such small droplets may simply fail to be separated at all. It is an object of the present invention to provide means that are able to reduce or avoid this problem.